1. Field
This invention relates to alarm management in a communications system. It is particularly, but not exclusively, related to alarm management in a mobile communications system.
2. Description of the Related Art
The amount of Internet traffic generated as a result of users having broadband connections is increasing. A significant cause of this increase is the transmission of multimedia, and in particular video.
Although broadband was originally provided via wired connections, there is a growing interest in broadband provided via wireless connections (so-called wireless broadband) and in particular in wireless mobile communication systems. As a consequence, home and office users using wireless broadband connections are becoming target customers for wireless network operators and service providers looking to increase average revenue per user and operating margin.
There are a number of different types of wireless mobile communication systems. Examples include second generation (2G) wireless mobile communication systems and more advanced systems such as third generation (3G) wireless mobile communication systems. A more advanced system than 3G, which is being developed within the 3rd Generation Partnership Project (3GPP), is referred to as long term evolution (LTE).
In one implementation, wireless broadband is provided by mobile terminals connecting to cells served by Femto base stations (Femto cells). Femto base stations are low-power wireless access points that have a cellular wireless network air interface to connect to compatible cellular mobile terminals, which are themselves connected to a mobile network operator's network using any suitable broadband connection, for example residential digital subscriber line (DSL) or cable broadband connections. As a result, the Femto base stations are connected to the core network through the Internet. In the case of 3GPP LTE networks, the Femto base stations are connected to a relevant serving gateway for data traffic and to a mobility management entity (MME) for signalling traffic through a Home eNodeB gateway or not depending on the implementation. In case of 3GPP 3G networks, the Femto base stations are connected to a Home NodeB gateway, which concentrates data and signalling traffic.
Femto base stations are essentially scaled-down versions of macro cell base stations (that is those serving conventional cells having a relatively large area which might be kilometers or tens of kilometers across). In general, Femto base stations are about the size of a WLAN access point, and provide enhanced cellular coverage to an area of about several hundred square meters. This is more than enough for small offices or homes.
In 3GPP terminology, Femto base stations, or home base stations, are called Home NodeBs or HNBs when referring to 3G applications and are called Home enhanced NodeBs or HeNBs when referring to LTE applications. The general term used to apply to both is H(e)NB. In the following, where the term “(e)” is included in the name of any network functionality, this indicates that the functionality can be applied both in 3G and LTE systems.
In functional terms, an H(e)NB comprises the combined functionality of a base station, that is a BTS/NodeB/eNodeB, and some of the functionality of a base station controlling element, that is a base station controller (BSC) or a radio network controller (RNC).
Using a Femto base station provides a capacity equivalent to a mobile network cell at low transmit powers. This may allow for increased mobile terminal battery life. In addition, mobile terminals can be simpler because they do not have to be capable of operating according to other wireless protocols, such as wireless local area network (WLAN). Using Femto base stations frees up a network operator's cellular network for other traffic and relieves congestion at cell sites. In addition, Femto cells employ a user's own power and broadband resources.